1. Field of the Invention
The present invention relates to an all-solid secondary battery, in particular to an all-solid lithium ion secondary battery and a method of manufacturing the all-solid lithium ion secondary battery.
2. Related Art
All-solid batteries, using an inorganic solid electrolyte and not using organic substance even in electrodes, are free from worries about leakage of organic electrolyte or gas generated from organic electrolyte, and therefore are expected to be safe batteries. Furthermore, the all-solid batteries are less likely to induce a side reaction other than battery reactions compared to liquid batteries, and therefore are expected to have a longer operating life compared to liquid batteries.
In an example of the all-solid batteries, a positive electrode layer and a negative electrode layer are respectively laminated and sintered on both sides of a solid electrolyte layer. In the all-solid batteries, constituent particles between or within the layers can be physically connected by sintering. However, in this case, there arises a problem that ion conduction resistance increases since a substance other than active materials or solid electrolytes generates during sintering at a sintered interface of electrode active materials and the solid electrolyte. Consequently, Patent Document 1 discloses that an uncalcined body of solid electrolyte layer composed of a solid electrolyte and an uncalcined body of electrode layer are laminated and these are calcined simultaneously for the purpose of forming a sintered body used for an inorganic solid electrolyte, for example. Here, Patent Document 1 also discloses that sintering of crystalline solid electrolyte or electrode active material is promoted by adding a glass body with a softening temperature of 700° C. or higher into at least a solid electrolyte layer or an electrode layer.
Furthermore, Patent Document 2 discloses an all-solid battery using a positive electrode which is composed of a solid electrode based on sulfide and a positive electrode active material coated with a lithium ion conductive oxide.
Furthermore, Patent Document 3 discloses a method in which when a solid electrolyte composed of a crystallized glass formed with a NASICON-type main crystal is prepared, connection is made with an electrode under a pre-crystallized glass condition and then crystallizing is performed.
Furthermore, Patent Document 4 discloses a glass which is obtained through ion exchange and has lithium ion conductivity.
[Patent Document 1] Japanese Unexamined Patent Application, Publication No. 2007-005279
[Patent Document 2] PCT International Application, Publication No. 2007/004590 Pamphlet
[Patent Document 3] Japanese Unexamined Patent Application, Publication No. 2009-224318
[Patent Document 4] Japanese Unexamined Patent Application, Publication No. 2010-275130